Something which could be accomplished through robotics that couldn't economically be accomplished using human labor would be maximizing the utilization of a very limited surface area (and the sunlight it receives), by repositioning plants to maintain ideal spacing as they grow, and as some are removed while others remain and new plants (or seeds) inserted among those already there.
This can be done using pots of various sizes on a platform, repotting plants as necessary. It might also be done using a grid or honeycomb-like support frame, each cell of which is large enough to accommodate a single mature plant of the largest variety to be grown this way, but which is also divisible into smaller cells - rectangular in the case of a grid, or a combination of hexagonal and triangular subsections in the case of a honeycomb - for seedlings and smaller plants.
This approach, because it would mean discrete positioning, would lend itself to automation. It would also position the soil surface at the same level for all plants, rather than having smaller pots hidden and shaded by larger pots. While something resembling repotting would still be needed, because a suspension system can have a soft underside, such as a loosely woven fabric pouch, made of biodegradable fiber, hung from a rigid frame, that repotting could be nothing more traumatic for the plant than positioning a smaller frame within a larger one and filling in between with potting soil, leaving the pouch in place to decompose while the plant's roots grow through it, a procedure which could be accomplished robotically, without the need for high precision. This can be repeated until the stem of the plant grows to the point that it no longer fits through the smallest subframe initially employed, which usually won't happen.
Like pots on a platform, when a plant is removed from the framework, the soil is typically removed with it, which can help with the control of pests and diseases. (Used soil, containing whatever is left of the pouches, which can simply be cut loose from the frames pieces, can be sanitized by inclusion in compost, which can hold a temperature between 120 and 160 degrees F, for several days, the peak temperature depending on the scale of the compost operation as well as on the initial ingredients and how it's managed.)